Wildlife Photography - PentaxForums.com
K3-II: 8.3 fps; weather-sealed, in-body image stabilization. To my mind, the latter is the single most important reason to buy Pentax if you're looking to photograph potentially fast or erratically moving subjects. Some Canon and Nikon lenses contain image stabilization features, but I don't think they work as well, plus you pay extra for that feature with every lens instead of once per body, and the best lens for what you want may not have it.
SMC Pentax-DA* 300mm F4 ED [IF] SDM (ideally to be potentially used in conjunction with a HD Pentax-DA 1.4x AW teleconverter).
Zoom lenses will be more problematic in the sharpness/detail department depending on aperture and where you are in the focal range, not that there aren't some great ones out there.
I don't have that stuff myself, although I've got an older FF version of the 300mm and a 1.7x FF TC. But, then, I didn't buy my cameras with the intention of dedicating any for wild nature. What I've suggested is what I'd have gotten if that had been my goal.